First asteroid gas sample delivered by the Hayabusa2 mission: A treasure box from Ryugu

Abstract

The Hayabusa2 spacecraft returned to Earth from the asteroid 162173 Ryugu on 6 December 2020. One day after the recovery, the gas species retained in the sample container were extracted and measured on-site and stored in gas collection bottles. The container gas consists of helium and neon with an extraterrestrial 3 He/ 4 He and 20 Ne/ 22 Ne ratios, along with some contaminant terrestrial atmospheric gases. A mixture of solar and Earth’s atmospheric gas is the best explanation for the container gas composition. Fragmentation of Ryugu grains within the sample container is discussed on the basis of the estimated amount of indigenous He and the size distribution of the recovered Ryugu grains. This is the first successful return of gas species from a near-Earth asteroid.

Role of Acetylene in the Chemical Evolution of Carbon Complexity

“…118 In addition to the absence of acetylene, the abundance of methane and ethane in the gas samples was low. 119 The reactions of acetylene formation in satellites are similar to those for the Jovian planets given in Table 2.…”

“…For example, the Hayabusa2 mission examined the asteroid 162173 Ryugu and returned samples from its surface to Earth in 2020. , Analysis of soluble organics revealed the presence of PAHs, heterocyclic compounds, carboxylic acids, amino acids, amines, etc . In addition to the absence of acetylene, the abundance of methane and ethane in the gas samples was low . The reactions of acetylene formation in satellites are similar to those for the Jovian planets given in Table .…”

Noble gas mass-spectrometry for extraterrestrial micro-samples: analyses of asteroid matter returned by Hayabusa2 JAXA mission

“…Several well-equilibrated aliquots of this gas were prepared 28 and distributed among different laboratories, where they were independently analysed using different mass spectrometers and gas preparation techniques. 29 We will not discuss the results of these works here but rather consider the head gas sub-samples as a perfectly homogenized noble gas standard. Fig.…”

Ryugu asteroid sample return provides a natural laboratory for primordial chemical evolution

“…Therefore, a careful workflow of sample recovery, sample return, and high-precision organic analysis of the freshest carbonaceous asteroid sample, without uncontrolled exposure to the Earth’s atmosphere 9 and biosphere 10 , is a critical mission for organic astrochemistry 6 , 11 , 12 (Fig. 1 ).…”